Identification and evolution of latrophilin receptor gene involved in Tribolium castaneum devolopment and female fecundity

Latrophilins (LPHs) are adhesion G-protein-coupled receptors comprising three paralogous forms (LPH-1, LPH-2, and LPH-3) and known receptors for -latrotoxin, which are involved in growth, development, adaptability, and schizophrenia and other diseases in vertebrates. However, the functions of LPH are poorly understood in most insects. Here, phylogenetic and synteny analysis indicated that LPH-1 and LPH-3 evolved separately from a common ancestor LPH-2. Then, latrophilin (Tclph) was cloned in Tribolium castaneum, and three alternatively spliced transcripts (Tclpha, Tclphb and Tclphc) were identified. All these three Tclphs were highest expressed at the early adult stage, and strongly expressed in central nervous system of adults. Larval RNA interference (RNAi) against Tclph caused 24% adult wing abnormal, 30% insect death, and led to 100% reductions in beetle fecundity. Fecundity deficiency was rescued by reciprocal crosses with wild-type females, but not males. And dissection results revealed that 63% of dsTclph female ovaries were atrophied. Further, exon-specific RNAi illustrated that neither knockdown of Tclpha nor Tclphc resulted in development defects and reductions in beetle fecundity. Thus, it indicated that Tclphb was essential for development and female fecundity in T. castaneum. Moreover, Tclph knockdown increased the expression of the foxo, plc, and pka genes, which most likely modulated the effects of Tclph on development and reproduction in T. castaneum.